Automating Surface Irrigation

AUTOMATION of surface irrigation offers exciting possibilities for today's irrigation farmer. It provides a means for improving water use efficiency and cutting labor requirements. Excessive water is often used in current irrigation methods; water application efficiencies usually do not average over 50 to 60 percent. Although many factors affect irrigation efficiency, the water facilities and management practices used by the individual operator have the greatest effect. Competition for available national water supplies is increasing rapidly. Irrigators eventually may have to justify their use of water. They may not always be permitted to use nearly twice the amount required to satisfy crop consumptive use requirements

Research Seeks Answers to Runoff Losses

Sediment has been labeled as one of the worst pollutants of our natural streams. While much erosion is natural, sediment production from cropland is a problem for many irrigators. Farmers have always been interested in conservation; however, in recent years increased public attention to conservation has caused irrigators to become even more concerned with limiting erosion from their lands. Stream size, slope, crop, soil, and water management practices are the principal factors that determine the amount of erosion. Researchers are studying the relative effects of these factors in causing erosion to obtain data that will identify those that are the most important and those that can be most readily controlled. This information can then be used to help irrigators minimize soil losses from their fields

Automatic Equipment for Surface Irrigation

Automatic and semi-automatic surface irrigation structures and systems are being developed to improve irrigation water management and conservation on the farm. Most mechanized structures may be classified as fully automatic or semiautomatic depending upon their method of operation. A fully automatic system operates without attention from the operator other than periodic inspections from one irrigation to the next. The need for irrigation and often the irrigation time periods, however, are still largely determined by the irrigator who usually has to turn water into the system. The semi-automatic system uses gates and checks which are normally tripped at a preset time by a mechanical timer or electrically. In addition to determining the need for irrigation, the irrigator also manually resets the structures or moves them from one location to another, or both, prior to each irrigation. With competition for available national water supplies increasing, some irrigation water users may be forced to use their water more efficiently. Automatic equipment provides a means of accomplishing this while at the same time saving labor. At a time when reliable farm help is difficult to obtain, and wage rates are increasing, an investment in automatic structures could be an economical alternative and may be more easily justified than in the past. Surface flooding systems using basins, borders or contour ditches are easiest to automate since the field topography allows the entire stream of water to be distributed over the soil surface. When furrows are used, however, the irrigation stream must be uniformly divided into many small streams directed into individual furrows. This requires furrow flow regulating devices or controls in addition to check and turnout structures

Israqua and ICID Irrigation Conferences

New developments in irrigation and drainage were discussed at two recent international conferences. The Tenth International Commission on Irrigation and Drainage (ICID) Congress on Irrigation and Drainage was held in Athens, Greece. The ISRAQUA '78 International Conference on Water Systems and Applications was held in Tel Aviv, Israel. Irrigation has expanded throughout the world during the past 2 or 3 decades. Most countries now depend on irrigated agriculture to increase and stabilize food and fiber production for their expanding populations. These international conferences, attended by engineers and policymakers involved in the design and operation of irrigation systems, provide a means to exchange experience and knowledge. Information and experience gained in one country often can be used in another. Some interesting and new approaches are described in this article

An Automated Single-Pipe Irrigation System

An automated single-pipe system was developed for both water conveyance and distribution to the field. The pipe has a flexible tube liner inside and is equipped with automated diverter valves. The valves direct water either through the flexible tube for conveyance to downstream pipeline sections or to the outside of the tube for distribution to the field through the pipe gates. The system is well suited for automating multiple-set gated pipe systems for both conventional and surge flow irrigation. Head loss coefficients were determined for the valves and the pipeline for both the conveyance and distribution modes. Field installation procedures are described. The cost of the single-pipe system is about 60% of that for an automated double pipe system

Automatic Mechanical Irrigation Gates

Small automatic irrigation gates for farm distribution systems are being developed to improve the efficiency of water use and to save labour. Two general classes of gates are described : (1) fully automatic gates which operate from the energy of water flowing in the ditch and which require a minimum of attention from the operator ; and (2) semi-automatic gates which require resetting or moving at each irrigation. The structures are designed to divert water for a predetermined period of time from a farm distribution ditch onto one portion of a field after another in sequence. They are normally used in pairs

Semiautomation of irrigated basins and borders: I. Single-function turnout gates

Two types of single-function, drop-closed gates for semiautomating irrigated basin and border systems are described Gate design, construction, and operational information are presented. Gates for both rectangular and pipe turnout openings were tested and evaluated in a 24 ha (60 acre) near-level basin system. Gates for pipe turnouts were also tested in a 10 ha (25 acre) border system. The gates provide greater operator convenience, and in the border system, even on a manual basis, increased water storage efficiency and reduced irrigation set time and labor. Systems and devices for controlling the gates are presented in another article

Mechanized Wheel and Belt Screens for Farm Irrigation Turnouts

ROTATING wheel and traveling belt trash screens were developed for farm canal turnouts to prevent trash and debris from entering farm irrigation systems. They are driven by electric motors or water-powered paddle wheels. The screens are particularly useful for automated irrigation systems. The head loss is small, and they are not adversely affected when the farm delivery is terminated by automated downstream valve closures while canal turnouts remain open. Different screens, bearings, and bushings were tested for this application. Hydraulic tests were conducted to determine head losses with different wheel screens

Automatic Water Control Structures for Surface Irrigation (Summarized)

Many improvements have been made in irrigation methods and equipment in recent years. However, surface irrigation has not benefited from automation and still requires much hand labor. In addition to this high labor requirement, an excessive amount of water is often used. This is particularly true in areas where water is relatively cheap and labor is scarce. Further improvement in surface irrigation methods and equipment using mechanized automated control structures will enable the farmer to apply water with a minimum of labor and to obtain maximum use from the water, thus conserving his resources

Semiautomation of basin and border irrigation

Basin and border irrigation systems use relatively large supply streams which require precise set times to optimize irrigation efficiency and to prevent dike overtopping and excessive runoff. During the past decade, these systems have greatly benefitted from advancements made in land grading technology using laser-guided equipment. Although this has increased distribution uniformity, reliably predicting the time required for water to advance to the end of a field is still often difficult. Advance time is influenced by variable water deliveries, variable soil intake rates within a given field and throughout the season, and by different stages of crop growth. Thus, the irrigator must make frequent trips to the field to observe the water's advance, which is particularly inconvenient at night. These problems can be reduced by semi-automating the irrigation system and by using sensors located near the lower end of a field to provide feedback to terminate irrigation of a given land. Semiautomation is usually preferred because of its simplicity and lower cost compared to more sophisticated systems. Semiautomated systems require manual input to either turn water into the system or to reset or reposition the structures and/or control devices. The next step toward system improvement during the coming decade is greater use of automated structures and controls to provide greater convenience for the irrigator, labor savings, and increased irrigation efficiency. Several different gate configurations and controls which are currently being field tested in both a level basin and a border system are described in this paper